The present invention relates to fluid flow control devices and more particularly to a continuously self-calibrating water flow control apparatus for utilization with a water flow system.
Automatic fluid control devices are presently in common use, particularly in association with water faucets or toilets. More specifically, it is known in the art to utilize motion detectors and object detectors, such as infrared, electrostatic or radar sensors, to detect the presence of an object within a detection area necessitating the activation of a water flow device.
Not all objects interposed within the detection area, however, should activate the water flow assembly. For example, while a hand placed in a sink should continuously activate a faucet, a towel accidentally dropped into the sink should not. Possible water wastage resulting from objects left indefinitely, unintentionally or through vandalism, in these detection areas poses a significant obstacle to the successful implementation of such automatic water flow control devices, particularly in public areas.
In general, one known solution to this problem includes timing devices to shut off water flow after a preset time following the faucet's activation. This, however, requires some method or device for reactivating water flow under the proper circumstances. One method is simply to deactivate water flow for a predetermined time period, thereafter permitting water flow upon the detection of an object or motion within the detection area. Another known method is to deactivate the water flow until the conditions that initially caused the water flow are removed. Thus, for example, if a towel were left in a sink, water flow would continue until the timing circuit deactivated the flow, which would remain deactivated until the towel was removed.
Both of the above-mentioned solutions result in further difficulties. If the fluid control device merely deactivates for a predetermined period, an object left in a sink indefinitely would cause the automatic faucet to repeatedly turn on and off, thereby still resulting in water wastage. On the other hand, if the fluid flow control device deactivates until the object in the sink is removed, the faucet is totally and unnecessarily inoperative. For example, a towel placed over the sink edge may initially activate the faucet. When the faucet deactivates after the preset time period, it will remain deactivated until the obstacle is removed. Someone subsequently attempting to operate the faucet would find that it would not work but might not realize that the towel must be removed to permit its use.
Still another difficulty encountered with automatic fluid flow control devices, such as are found in water faucet assemblies, involves calibration upon installation and changed ambient environments. When installed, such devices must be manually calibrated. That is, the device must be adjusted to define a detection area adjacent to the faucet such that when an object is interposed within this detection area, the faucet is activated. Such manual calibration is time consuming and results in inconsistent detection areas. For example, one faucet may be activated when a hand is placed three inches from the faucet, while an adjacent faucet might be activated at four inches.
Furthermore, a change in the ambient environment may require recalibration to ensure proper operation of the faucet. For example, infrared sensor devices are heat sensitive. Accordingly, they may activate a faucet prematurely when room temperature is abnormally high or fail to activate the faucet when room temperature is abnormally low. Specifically, infrared devices have been known to fail to activate a faucet when a user's hands were too cold.
Infrared sensors are also color sensitive. Therefore, if a new sink is installed having a brighter color, the automatic water flow control device may require recalibration to prevent inappropriate faucet activation.
Thus, it is desirable to have a fluid flow control device that prevents fluid wastage due to objects left indefinitely within the detection area yet permits fluid flow thereafter under appropriate conditions. It is furthermore desirable to have such a device that self-calibrates upon installation and changes in environmental conditions.